What happens if you cut the engines mid air, can you turn them back on and save the P3

[BigKenny]

Kenny .. read this from the manual - especially the last bit I highlighted in pink

No need to be paranoid. You would have to be flying like a crazy chimp to CSC mid-flight. And if you fly like that you're not far from crashing anyway.
It's not something that happens in normal flight.

Thanks, i missed that line in the manual. I don't think I have ever come close to doing that, but I don't want to realize it when it's too late!

 

[sergekouper]

Air resistance has a significant impact on a falling Phantom with the shape and the propellers providing drag.
It doesn't continue to accelerate but reaches a terminal velocity that varies between 28-35 mph.
GPS shouldn't have much to do with it as the GPS is only used to provide horizontal position.

8 to 35mph for terminal velocity doesn't seem much to me as the phantom is already able of this speed horizontally... I don't know how you calculated this but I would be interested to know. Even if the drag was 50% wich is definitely not the case (I would estimate it at max 20%) the fall should be much faster.
Anyway, even at that speed, if the motors are stopped 5 sec and restart, they will need at least another 2 sec for the CSC to start and maybe another 5 to reach the full throttle. In just 7sec, the phantom will have fallen more than 100m before starting its slowing down and recovery.
Where the GPS mode has a major role is to balance the quad horizontally, and stop crazy drifts after the manoeuver. This is the only way to stabilize it, so yes it would be essential in that case. The problem is that it doesn't give the full power available to the engines, and I wonder how long it would really take to stop the fall efficiently.

Now I can say that I have kind of experienced something not similar but near I guess. I have made some 360 flips over in manual with my P2 , he he... going very high, idle the throttle and roll max to the right. At that very moment, the phantom is almost stil, and start a slow flip over. this moves loses probably about 7/8 meters with my stock gains.
Swiching back to GPS when the quad is at 90 degrees brings it to horizontal but looses quite a lot of altitude. probably at leat 20m
Switching back to GPS at the end of the looping and it falls like a stone for I estimate at least 30m, and another 10 meters when you hear the engines reving like mad, but late and not that fast anyway.
Throtteling manual again at the end of the looping saves the day. with a minimal loss of altitude. would say about 5 m.

My point is: I don't think that the phantom can recover from a stop and start in the air... I wouldn't try that.

 

[RiZe-TommyGun]

This happened to me when my P2V+ malfunctioned and all of a sudden took off straight up. I was holding down on the left stick to try and slow the climb, after holding it for 3 seconds the engines just cut out. It started falling like a stone and flipping over and over. I managed to turn the engines back on maybe 100 feet from the ground and it turned right side up, I then gave it full throttle to slow the rapid descent but it wasn't enough. It smashed into the concrete in a parking lot and the battery flew out stopping the engines instantly, it then tipped over. All in all I lost 2 props and the landing gear. I already had a carbon fiber landing gear I planned on installing so I had it up and running again the next day. I still have no idea what happened but I re-calibrated everything. I think if it had some more time it would have leveled out.

 

[N017RW]

This happened to me when my P2V+ malfunctioned and all of a sudden took off straight up. I was holding down on the left stick to try and slow the climb, after holding it for 3 seconds the engines just cut out. It started falling like a stone and flipping over and over. I managed to turn the engines back on maybe 100 feet from the ground and it turned right side up, I then gave it full throttle to slow the rapid descent but it wasn't enough. It smashed into the concrete in a parking lot and the battery flew out stopping the engines instantly, it then tipped over. All in all I lost 2 props and the landing gear. I already had a carbon fiber landing gear I planned on installing so I had it up and running again the next day. I still have no idea what happened but I re-calibrated everything. I think if it had some more time it would have leveled out.

This does not happen unless or until no vertical motion is detected.

There's more to your incident like maybe a malfunctioning baro altimeter.

 

[emilewski]

I would prefer DJI put CSC function into a dedicated kill switch on the remote with a flip cover you have to lift up first and then combo that with a stick movement. Stick position alone for a CSC is not a good idea imho.

 

[omarkatwe]

My p3 crushed in that way,
By mistake i turned the motors off in the sky for heigh more than 50 meters, when i tried to turn it on again it didn't works. The drone fall down and crashes

 

[RiZe-TommyGun]

This does not happen unless or until no vertical motion is detected.

There's more to your incident like maybe a malfunctioning baro altimeter.

Believe me I know, I didn't perform a CSC it cut out like it had been landed and there was no vertical motion. The day before this happened I was flying indoors (like an idiot) and the prop wash caught a calendar hanging on the wall that then sucked up into the props, the P2 hit the door and fell on the ground. I think something got messed up on the little crash and then the next time I flew, I had the big crash.

That crash actually taught me a lot about safety and properly operating a giant flying blender. I now know that any kind of little crash or tip over, calls for a complete re-calibration, at least with the older P2's. I have yet to even have a prop touch the ground on my P3P.

 

[N017RW]

Believe me I know, I didn't perform a CSC it cut out like it had been landed and there was no vertical motion. The day before this happened I was flying indoors (like an idiot) and the prop wash caught a calendar hanging on the wall that then sucked up into the props, the P2 hit the door and fell on the ground. I think something got messed up on the little crash and then the next time I flew, I had the big crash.

That crash actually taught me a lot about safety and properly operating a giant flying blender. I now know that any kind of little crash or tip over, calls for a complete re-calibration, at least with the older P2's. I have yet to even have a prop touch the ground on my P3P.

Good news on the lessons learned.
You can't be an expert until you make all the mistakes.

(You're actually flying 4 Blenders!)

 

[Meta4]

28 to 35mph for terminal velocity doesn't seem much to me as the phantom is already able of this speed horizontally... I don't know how you calculated this but I would be interested to know. Even if the drag was 50% which is definitely not the case (I would estimate it at max 20%) the fall should be much faster.

My point is: I don't think that the phantom can recover from a stop and start in the air... I wouldn't try that.

The info came from the youtube video by the "genius" that flew to a great height only to realise that descending took longer than he had battery for. He tried CSC to descend and managed to restart successfully. His master plan came unstuck when he still ran out of battery and fell the last few hundred feet.
He had dashware gauges on the video that showed vertical speed and height and from that you could see that the speed was varying with the Phantom and props wobbling on the way down.
Unfortunately for science he removed the video a couple of months ago.

 

[Youngbill]

Alright guys, I had to do it!
http://www.gofundme.com/zegt4f7

Please share this and we'll see if it gets any traction.

Bill

 

[adjmirealty]

I would prefer DJI put CSC function into a dedicated kill switch on the remote with a flip cover you have to lift up first and then combo that with a stick movement. Stick position alone for a CSC is not a good idea imho.

Someone send this to DJI ASAP I love the idea... We all want simplicity even experienced flyers

 

[ScottyT]

Alright guys, I had to do it!
http://www.gofundme.com/zegt4f7

Please share this and we'll see if it gets any traction.

Bill

Hah. You just joined and that is your first post...? I'd prefer to give a little cash to someone that has more credentials. But hey, try your luck. Probably best you start your own thread about your endeavors and detail your plan to test the mid-air CSC better. Otherwise people are just giving some random money to buy a phantom.

 

[ScottyT]

Someone send this to DJI ASAP I love the idea... We all want simplicity even experienced flyers

Not going to fly. The old school crowd see no problem with CSC the way it is, it's always been that way.

 

[N017RW]

It's got nothing to do with old school.
It's all economics and engineering.

It is a very clever use of existing hardware and a never-used-in-flight stick combo.

 

[ScottyT]

It's got nothing to do with old school.
It's all economics and engineering.

It is a very clever use of existing hardware and a never-used-in-flight stick combo.

Best we not go there.

 

[jlo]

Alright guys, I had to do it!
http://www.gofundme.com/zegt4f7

Please share this and we'll see if it gets any traction.

Bill

ROFL...yeah.....ah no.

 

[beatnik]

Yes! A CSC will happen any time you give the command, regardless of where the P3 is physically at. The CSC is a safety feature. There's not much point discussing the merits, DJI has decided the CSC is necessary and we are stuck with it.

CSC will be initiated by bringing both sticks down and to any of the four bottom corners at the same time: bottom inside, bottom outside, bottom left, bottom right. This is clear covered in the manual.

..And hold throttle straight down three secs. That one bothers me. I've seen many people grab the bird in the air and power off this way with one hand on stick. But what if you need to descend rapidly from altitude? The reaction would be to pitch down and hold....Uh Oh.

I've been very careful not to hold pitch all the way down. Has this happened or is there some altitude level above which the throttle down 3 does not work? ( I don't mind the other CSC positions)

 

[N017RW]

The left stick only down position takes 3 seconds to stop the motors so the FC can determine if the quad is stationary or not. i.e. no longer descending.

 

[Meta4]

..And hold throttle straight down three secs. That one bothers me. I've seen many people grab the bird in the air and power off this way with one hand on stick. But what if you need to descend rapidly from altitude? The reaction would be to pitch down and hold....Uh Oh.

Uh Oh indeed.
Do you really think DJI engineers can be smart enough to design the P3 but make the common descent method stop the motors?!!!!
Really???
You can descend full stick down for 33 seconds or more quite safely.
That's the way most Phantom owners do it.

 

[Mako79]

I would prefer DJI put CSC function into a dedicated kill switch on the remote with a flip cover you have to lift up first and then combo that with a stick movement. Stick position alone for a CSC is not a good idea imho.

Disagree... In the case of an emergency.. by the time you find the flip cover and enable and then CSC, your child would have lost 10 fingers and 3 toes.